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Questions and Answers
How does high ATP concentration affect phosphofructokinase activity in glycolysis?
How does high ATP concentration affect phosphofructokinase activity in glycolysis?
High ATP concentration inhibits phosphofructokinase activity, slowing down glycolysis.
What is the role of pyruvate dehydrogenase complex in the conversion of pyruvate to acetyl CoA?
What is the role of pyruvate dehydrogenase complex in the conversion of pyruvate to acetyl CoA?
The pyruvate dehydrogenase complex catalyzes the oxidative decarboxylation of pyruvate to form acetyl CoA.
What are the primary components of the pyruvate dehydrogenase complex?
What are the primary components of the pyruvate dehydrogenase complex?
The primary components are pyruvate dehydrogenase, dihydrolipoyl transacetylase, and dihydrolipoyl dehydrogenase.
Explain the significance of coenzymes derived from Vitamin B complex in the function of the pyruvate dehydrogenase complex.
Explain the significance of coenzymes derived from Vitamin B complex in the function of the pyruvate dehydrogenase complex.
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Describe how glycolysis is connected to lipid metabolism.
Describe how glycolysis is connected to lipid metabolism.
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Explain the role of ATP in the phosphorylation steps of glycolysis.
Explain the role of ATP in the phosphorylation steps of glycolysis.
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What is the difference between aerobic and anaerobic glycolysis in terms of end products?
What is the difference between aerobic and anaerobic glycolysis in terms of end products?
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How does the absence of mitochondria in RBCs affect their energy production?
How does the absence of mitochondria in RBCs affect their energy production?
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Describe the enzymatic roles of phosphoglycerate kinase and pyruvate kinase in glycolysis.
Describe the enzymatic roles of phosphoglycerate kinase and pyruvate kinase in glycolysis.
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What is the significance of 2,3-DPG in relation to oxygen delivery in tissues?
What is the significance of 2,3-DPG in relation to oxygen delivery in tissues?
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Study Notes
Glycolysis
- Glucose breakdown to pyruvate via 10 steps
- Occurs in the cytoplasm
- Anaerobic process (without oxygen)
- Aerobic process (with oxygen)
- Produces 2 ATP molecules per glucose molecule
- Requires NAD+ as an electron acceptor
Stages of Glycolysis
- Phosphorylation: Glucose is phosphorylated to glucose-6-phosphate
- Isomerization: Glucose-6-phosphate is converted to fructose-6-phosphate.
- Second phosphorylation: Fructose-6-phosphate is phosphorylated to fructose-1,6-bisphosphate
- Cleavage: Fructose-1,6-bisphosphate cleaved to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.
- Interconversion: Dihydroxyacetone phosphate is converted to glyceraldehyde-3-phosphate.
- Oxidation: Glyceraldehyde-3-phosphate is oxidized to 1,3-bisphosphoglycerate
- Substrate-level phosphorylation: 1,3-bisphosphoglycerate is dephosphorylated to 3-phosphoglycerate, producing ATP
- Isomerization: 3-phosphoglycerate is converted to 2-phosphoglycerate.
- Dehydration: 2-phosphoglycerate is dehydrated to phosphoenolpyruvate
- Substrate-level phosphorylation: Phosphoenolpyruvate is dephosphorylated to pyruvate, producing ATP
Glycolysis in Red Blood Cells (RBCs)
- RBCs lack mitochondria.
- Rely solely on glycolysis for energy production.
- RBC glycolysis is known as the Rapoport-Luebering cycle (RL cycle).
- Produces lactic acid.
2,3-Diphosphoglycerate (2,3-DPG)
- Promotes the release of oxygen from hemoglobin in tissues.
- Prevents tissue hypoxia.
Energy Calculation
- Aerobic glycolysis: Produces 8 ATP molecules (net gain of 6 ATP).
- Anaerobic glycolysis: Produces 2 ATP molecules (net gain of 2 ATP).
Regulation of glycolysis
- Amphibolic pathway: Catabolic for glucose breakdown and anabolic for glucose synthesis.
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Irreversible enzymes:
- Hexokinase: Inhibited by glucose-6-phosphate.
- Phosphofructokinase (PFK): Inhibited by ATP and citrate.
- Pyruvate kinase: Inhibited by ATP.
Importance of glycolysis
- Main source of energy for cells.
- Provides pyruvate for the citric acid cycle.
- Links carbohydrate and lipid metabolism.
Citric Acid Cycle (Krebs Cycle)
- Occurs in the mitochondria of cells
- Starts with acetyl-CoA to produce ATP
- 8 steps involve oxidation reactions
- Produces CO2, NADH and FADH2
- Requires NAD+, FAD, and coenzyme A.
Oxidative Decarboxylation
- Conversion of pyruvate to acetyl-CoA.
- Occurs in the mitochondrial matrix
- Catalyzed by the pyruvate dehydrogenase complex.
- Requires NAD+ and coenzyme A.
- Yields 1 NADH, 1 CO2, and 1 acetyl-CoA.
Coenzymes
- Essential for pyruvate dehydrogenase complex function.
- Includes:
- Thiamine pyrophosphate (TPP) (from Vitamin B1)
- Lipoic acid
- Coenzyme A (from pantothenic acid)
- Flavin adenine dinucleotide (FAD) (from vitamin B2)
- Nicotinamide adenine dinucleotide (NAD) (from niacin)
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Description
This quiz covers the glycolysis pathway, detailing the 10 steps involved in the breakdown of glucose to pyruvate. Learn about the stages including phosphorylation, oxidation, and ATP production while understanding the aerobic and anaerobic processes. Test your knowledge on this essential metabolic pathway!
